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Chapter 27: Environmental MicrobiologyBe able to:
Ch. 27 Environmental Microbiology
Microbial Ecology:§ relationship of microbes with each other and their environment§ huge effect on soil, water, our food§ Major ecosystems§ Oceans, rivers, lakes, deserts, marshes, grasslands, forests and tundra3 main levels of nutrient acquisition exist in ecosystems• Primary producers:§ Autotrophs - Convert CO2 to organic materials§ Photoautotrophs - use sunlight for energy§ Plants§ Algae§ Cyanobacteria§ Anoxygenic phototrophs§ Chemoautotrophs§ Oxidize inorganic compounds for energy§ serve as food source for consumers and decomposers3 main levels of nutrient acquisition exist in ecosystems• Consumers:§ heterotrophs§ use organic material created by producers§ Herbivores eat primary producers§ primary consumers§ Carnivores consume herbivores§ Secondary consumers§ Carnivores that eat other carnivores§ tertiary consumers3 main levels of nutrient acquisition exist in ecosystems• Decomposers:§ heterotrophs§ digest leftovers of primary producers and consumers§ detritus ( fresh or partially decomposed organic matter)§ bacteria and fungi - key players in decomposition§ mineralization§ complete breakdown of organic molecules to inorganic moleculesMetabolic Diversity§ Few places within organisms that are sterile§ No place in the world that is sterile§ Microbes live in a variety of habitats due to their abilities:§ To use a variety of carbon & energy sources§ To grow under different physical conditions§ Extremophiles live in extreme§ pH§ Temperature§ SalinityMicrobial Habitat§ Aquatic§ Marine§ Freshwater§ Terrestrial§ Air§ soil§ composition of microbes dependent on soil conditions§ Associations with insects plants and animalsAssociations with Animals§ normal bacterial flora of humans and other animalsBioluminescent bacteria:§ associate with animals for food and protection§ Fish: Flashlight fish and luminescent bacteriaAssociations with Insects§ Ants - live in associations with fungi§ Aphids - live in associations with bacteriaAssociations with PlantsBacteria association with plants§ Agrobacterium§ produce plant tumors to gain nutrient§ Rhizobium - mutually beneficial relationship with plants (nitrogen fixation)Biogeochemical Cycles§ Recycling (oxidation and reduction) of chemical elements by microorganismsCarbon CycleThe Nitrogen CycleNitrogen fixers§ fix nitrogen§ most common is Rhizobium§ Gram-negative rods§ Infect roots of legumes ŕ root nodules.§ Nodules where nitrogen fixation takes place.The Sulfur CycleThe Phosphorous Cycle§ Phosphorous exist primarily as phosphate ions (PO43-)§ cycle involves changes from:§ soluble to insoluble forms§ organic to inorganic forms based on pH§ no volatile form to be loss to the atmosphereDegradation of Synthetic Chemicals§ Natural organic matter is easily degraded by microbes§ Xenobiotics are resistant to degradationDecomposition by Microbes§ Bioremediation§ Use of microbes to detoxify or degrade pollutants§ Bioaugmentation§ Addition of specific microbes to degrade pollutant§ Composting§ Arranging organic waste to promote microbial degradationControlling environmental pollutants§ current methods are incineration or storage in land fills, which result in§ more pollution§ health risks§ bioremediation§ inexpensive§ publicly accepted§ non-polluting (ideally)§ in situ treatment (at the site)BiofilmsBiofilms: polysaccharide encased microbe community§ Beneficial for bacteria:§ adherence to surfaces§ share nutrients§ protection from harmful factors§ Problems for us:§ growth in hospital water reservoirs§ serious consequences in hospitalized patientsFreshwater ZonationWater Quality§ Microbes§ present in water§ can be filtered from groundwater§ drinking and recreational water§ transmit pathogens to humanColiforms§ Aerobic or facultatively anaerobic, gram-negative, non–endospore forming rods that ferment lactose to acid + gas within 48 hr, at 35°C§ Indicator organisms§ Used to detect fecal contaminationWastewater Treatment§ sewage composed of all materials of household plumbing system§ Effective sewage treatment:§ Eliminate potential pathogens and toxic materials§ Decreases organic content in sewageMunicipal Sewage Treatment
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